A contribution to the discussion on the safety of air weapons

Abstract

Firearms legislation in the UK stems from the Firearms Act 1968 with its definition of a firearm as a lethal barrelled weapon of any description. The Act allows certain exceptions to be held without licence, most notably air weapons although these are limited by The Firearms (Dangerous Air Weapons) Rules 1969 and related regulations to below 12ft lb (16.3J) for air rifles and below 6ft lb (8.1J) for air pistols. Despite this there are occasional fatalities, typically 1 or 2 each year in the UK, from legally owned air weapons. In the USA there are over 20,000 visits each year to emergency departments due to injuries from air weapons and paintball guns. Despite this, limited research appears to have been carried out into the safety of air weapons and the present study tries to address this. Fresh samples of animal tissue were obtained from an abattoir or butcher and were embedded in ballistic gelatin. Pig heart, lung, liver and shoulder were used. By firing pellets into gelatin alone and into the combination of the gelatin and animal tissue it was possible to compare gelatin as a model for these tissues. The depth of penetration was similar but the residual track appeared to remain more open in the animal tissue. Pellets penetrated completely through the organ, with total penetration of gelatin and organ being typically around 10-15cm. Samples of pig, cow and chicken skin were placed in contact with the gelatin or embedded in the gelatin to simulate the effect of skin on penetration into a body. Chicken skin had no effect, pig skin stopped the pellet and cow skin was perforated by the pellet. If cow skin was embedded in the gelatin there was little effect on the total amount of penetration, but cow skin on the front surface of the gelatin reduced penetration by about 30%. Computed tomography was used to examine the pellet track and to calculate the volume of damage produced. However, due to the similar densities of gelatin and organ a technique had to be developed to differentiate phases. A barium salt paste was applied to outer surfaces and iodine solution or barium nitrate solution containing red food colouring was injected into the pellet track to enhance the contrast of the track. The track through the gelatin tended to enclose itself whereas the track through the organ remained more open, presumably due to the inhomogeneity of the fibrous nature of the tissue. Pellets were also fired at construction materials (wood, plasterboard and brick) and computed tomography used to determine the volume of damage created. Pellets perforated single layers of wood and plasterboard and would embed in a second layer. However, if the two layers were in contact the pellet did not penetrate the first layer. An air rifle pellet could therefore perforate house construction materials, although the resultant kinetic energy would be low and further damage would be limited. Some of the possible physical parameters are discussed that might help predict the degree of damage caused, but from this study it is not possible to define a limi...

The interaction between clothing and air weapon pellets

“…The jacket weave has not formed a cup, possibly due to the higher tensile strength of the thicker yarn, but there is evidence of tearing of the fibres from the yarn. In previous studies with animal and bird skin placed in contact with ballistic gel it has been observed that the combination is stronger than when skin was embedded in the gel [4] and in unpublished work on building materials it has been found that when layers of wood or plasterboard are in contact with each other, air rifle pellet penetration is reduced compared with cases where an air gap existed between the layers. It is thought that there is mutual support between the layers to absorb the energy of impact.…”

“…Other studies have investigated the missile energy necessary to penetrate skin [17] and it has been shown that an air-skin-gel boundary can behave differently from an air-gel-skin-gel boundary [4]. It is therefore of interest to consider cases where nonpenetration occurred.…”

“…There has also been some interest of late in studying air weapons to better understand their wounding potential. Wightman et al [3,4] have studied the interaction of air weapon pellets on different materials embedded in ballistic gel (bone, heart, lung and liver). Meng et al [5] have studied the effect of ambient temperature on air rifle and found an increase of muzzle energy density (muzzle kinetic energy divided by pellet cross sectional area) from 65 to 81 J cm -2 (a 24% increase) as temperature rose from 15 to 28 o C (a 4.5% increase in absolute temperature).…”

Laparoscopic retrieval of an intra-abdominal air gun pellet

“…Their ballistic pattern of injury is poorly characterised compared with traditional firearms 3. One study4 investigating the ballistic profile of airgun pellets noted a difference between hunter (pointed) and bulldog (round ended) pellets. The bulldog pellet was associated with more tissue tearing and subsequently causing a higher morbidity.…”

Shot Through the Heart—Firepower and Potential Lethality of Air Weapons

“…Some authors imply that "dieseling" increases muzzle velocity (12,22). Wightman et al (23) have demonstrated that a pellet shot with accompanying "dieseling" effect had a 33% higher speed than one shot without the use of excess oil in the barrel. We believe that putative increase in velocity and kinetic energy in cases of "dieseling" depends on the quantity of oil excess and the extent of combustion of that oil.…”